1. Field of the Invention
The present invention relates to a treadmill, and more particularly to a treadmill having a changeable or adjustable suspension system for changeably or adjustably supporting a treadmill deck and for providing a variable impact restraint to the users.
2. Description of the Prior Art
Typical treadmills comprise a treadmill deck supported in a base frame or treadmill base, and an endless belt engaged around the treadmill deck for supporting users. A spring structure may further be provided and disposed between the treadmill base and the treadmill deck for providing resiliency or a cushioning effect to the users.
For example, U.S. Pat. No. 5,827,155 to Jensen et al. discloses one of the typical treadmills comprising an adjustable spring structure having a longitudinally extending leaf spring adjustable to different resilience with a slidable adjustment bar. However, the adjustment bar may not be precisely moved or adjusted relative to the treadmill base and also may not be easily adjusted or operated by the users.
U.S. Pat. No. 5,993,358 to Gureghian et al. discloses another typical treadmill comprising an adjustable or controllable suspension system having spring mounts, and a controllable device for providing the user-variable impact restraint. However, the controllable suspension system comprises a rather complicated configuration that may not be easily manufactured and that is adverse for marketing purposes.
U.S. Pat. No. 6,013,011 to Moore et al. discloses a further typical treadmill comprising elongate springs of adjustable stiffness for absorbing impact loads imparted on the deck by the users. However, the elongate springs may not be easily adjusted to different resilience.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional suspension systems for treadmills.